OSU Department of Pathology

Anatomical Pathology Interesting Case Conference

Microscopic Description:

Histology revealed multiple papillary fronds with fibrovascular cores lined by benign squamous cells. No nuclear atypia or stromal invasion is seen.

IHC: CK 20-, CK7-, basal layer stains Ki-67+.

Discussion:

Squamous papilloma is a rare, benign proliferative lesion arising from bladder urothelium. Pure squamous cell carcinoma of the urinary bladder is rare compared to urothelial carcinoma but squamous differentiation (intercellular bridges and/or keratinization)is seen in 21% of urothelial carcinomas of the bladder.

It often presents as gross hematuria, severe dysuria and lower abdominal discomfort.

Grossly, it appears whitish, exophytic lesion(size 0.4 to 1.2 cm ) at the mucosa. Can mimic invasive urothelial tumor.

Microscopically, multiple papillary fronds composed of papillary cores covered by squamous epithelium without koilocytic atypia, dysplasia, mitosis or stromal invasion. Keratinization can be seen on the surface.

IHC: CK 20/7-, low Ki-67 positivity in basal layer, p63+ / HPV DNA -.

Treatment involves surgical removal via transurethral resection of the bladder tumor (TURBT).

Timely follow up cystoscopy at 3/6 months is required as recurrence has been reported in several cases.

References:

Miliaras D, Vakalopoulos I, Anagnostou E. Squamous cell papilloma of the urinary bladder endoscopically mimicking cancer. Case Rep Pathol. 2013;2013:486312. doi: 10.1155/2013/486312. Epub 2013 Sep 18.

Busch C, Johansson SL. Urothelial papilloma. In: Eble JN, Sauter G, Epstein JI, Sesterhenn IA, editors. Pathology and Genetics of Tumours of the Urinary System and Male Genital Organs. 3rd edition. Lyon, France: IARC Press; 2004. p. p. 113.

Mohamed A, Khalil IA, Aldeeb M, Wazwaz B, Al-Ani A, Al-Jalham K. Squamous cell papilloma a rare urinary bladder tumor, case report and operative video. Urol Case Rep. 2022 Apr 4;43:102074.

Gustafson P., Fenster H.N., So A.I. Urethral squamous cell papilloma: case report and literature review. Can Urol Assoc J. 2014;8(5-6):E364–E365. doi: 10.5489/cuaj.1582.

 

Gorkem A, Uzun H, Gucer H, Dil E, Yazar S, Orman E. A Rare Case of Bladder Tumor: Squamous Cell Papilloma. New J Urol. 2025;20(2):117-120. DOI : 10.33719/nju1630050.

Case Images